Phoenix Packaging cell line transfection

Hello everybody,
I have the following problem:
I'm trying to transiently transfect eco phoenix cells in a 6-well-plate. I plated them out (2* 10^5 cells/well), but after transfection (2ug DNA, 6ul fugene and 200ul optimem per well), all phoenix cells become apoptopic. Has anybody a clue what could have gone wrong? I checked for contamination of the medium (it was not contaminated), there's also no contamination visible in the wells themselves. And the Phoenix cells weren't grown too dense before, and looked fine in the culture flask and after seeding them into the well plate, that's why I guess it has sth to do with the transfection step.
Troubleshooter